[triodesteve]

Gang, I have a TVC (not a S&B) that I have used for a few years with great success. it was custom wound for me to interface between my Sony SACD player and a 300b amp. I then changed to a Final Labs ss amp and everything was was still hunky dory (is that how you spell it?). Now I've added a Final Labs phono stage and I've got problems.
The phono stage has an output impedence of 60 ohms. When I play my phono stage thru the TVC, it sounds as though everything below 200Hz is being cut off. Is there a way to remedy this without going active, and keeping the TVC "sound" that I so like?

Thanks,Steve

[John Chapman]

Hello!

Nice stuff you have to play with! A couple things I can think to check:

1- The 60 Ohms output impedance is really very low - so low it would be worth checking to see if that is that actual figure. The sony cd player likely is a bit higher than that anyway so from an impedance point of view the phono stage should be better.

2- Check that the wiring to the TVC from the phono stage does not invert phase. Some winding geometries really do not like inverted phase with single ended wiring.  The MK II S&B trannie was like this - although it was the high end and not the low end that would suffer when connected wrong. The is a long shot......

The difference you describe are not subtle at all! If the output impedance of the phono stage is actually much higher than the 60 ohms then it could be the culprit if the transfomrer is rather low inducatnce (a result of the tvc's construction - number of turns - core, etc). That combination of high output impedance and a low inductance (resulting in a low impdedance that the source 'sees') would cause a low end roll off.

If the fellow who made the TVC is local  to you he likely has some test gear and could measure the TVC? sacd/phono stage and compare. In a pinch you could use a test disk for subwoofers along with a scope and have a look at the waveform at frequencies below 300 hz or so.

Just a few ideas to get started......

Thanks!

John

[triodesteve]

Thanks for your help.
Steve